Waste-heat boilers and like gas/liquid heat transfer systems

ABSTRACT

A waste-heat boiler, for use in a system having two units in tandem in the direction of gas flow and with at least one unit having a valved bypass, has a three-section cylindrical housing in which a plurality of heat-exchange pipes extend axially. At one housing end is a gas inlet and at the opposite end a gas outlet. An outer row of the pipes is welded together to form a gastight wall that defines an annular insulating chamber with the housing interior. Another such circular row of pipes forms another wall having openings at each end near the inlet and outlet. This other wall forms an annular gas chamber with the first-mentioned wall, in which chamber the rest of the pipes are located. A central, axial bypass passage through the boiler is pipe-free and has a valve for blocking gas flow and forcing air through the other chamber. The three housing sections are axially displaceable relative to one another and the two walls are similarly relatively displaceable, the outer wall being fixed to the top housing section.

nited States Patet FOREIGN PATENTS 869,394 5/1961 GreatBritain l22/7 1,354,149 1/1964 France 122/7 Primary Examiner- Kenneth W. Sprague Att0rneyl(arl F. Ross ABSTRACT: A waste-heat boiler, for use in a system having two units in tandem in the direction of gas flow and with at least one unit having a valved bypass, has a three-section cylindrical housing in which a plurality of heat-exchange pipes extend axially. At one housing end is a gas inlet and at the opposite end a gas outlet. An outer row of the pipes is welded together to form a gastight wall that defines an annular insulating chamber with the housing interior. Another such circular row of pipes forms another wall having openings at each end near the inlet and outlet. This other wall forms an annular gas chamber with the first-mentioned wall, in which chamber the rest of the pipes are located. A central, axial bypass passage through the boiler is pipe-free and has a valve for blocking gas flow and forcing air through the other chamber. The three housing sections are axially displaceable relative to one another and the two walls are similarly relatively displaceable, the outer wall being fixed to the top housing section.

PMENTED mm SHEET 1 my 3 r I 1 Joachi Kummel INVENTOR.

PATENTEU BEBE! m SHEET 3 BF 3 l N VENTOR Attorney WASTE-HEAT BOILERS AND LIKE GAS/LIQUID HEAT TRANSFER SYSTEMS FIELD OF THE INVENTION The present invention relates to a gas-liquid heat-exchange unit and, more particularly, to a waste-heat boiler intended for use with cracking gases, power-plant combustion waste gases, power fluids and the like.

BACKGROUND OF THE INVENTION A waste-heat boiler generally consists of a cylindrical housing through which extremely hot, often in the neighborhood of 1,000 C., compressed gas is passed in which are mounted coils or other heat-exchanger means for absorbing the heat of the gas for use elsewhere. Water can be boiled with this heat and thence used as steam to run turbines or the like. Further more, the heat-exchange unit serves to lower the temperature of the gas upon which it operates to acceptable levels for other uses or for disposal.

Such devices present several problems. There is usually no means of efficiently regulating the gas flow through them since, when no heat is needed, the circulation of liquid through the coils cannot simply be stopped because the inevitable large buildup of heat would assuredly rupture the coils and otherwise ruin the device.

Furthermore, since such devices are used often in conjunction with gases carrying any of a multitude of contaminants, their interiors must be periodically cleaned. Ports having doors are generally provided to give access to the device during this cleaning operation. These doors, however, present a leak hazard and usually make the thorough insulation of the boiler impossible.

Another problem is the requirement for thermal insulation, the interior of the housing being often lined with refractory brick or the like to prevent excessive heat loss. Such brick greatly increases the bulk and cost of such a boiler. It should be noted that conventional waste-heat boiler systems may include two such boilers in tandem or series in the direction of gas flow, both of which can be provided with tube bundles or nests for the passage of water, but one of which is provided with a valved bypass for its tube nest.

OBJECTS OF THE INVENTION It is, therefore, a general object of the present invention to provide an improved gas-liquid heat-exchange unit for the above-described purposes.

A more specific object is to provide a waste-heat boiler which overcomes the above-mentioned disadvantages, i.e. which is easy to clean, whose heat-exchange rate can be easily regulated, which is readily assembled and taken apart, and which is relatively compact and inexpensive.

SUMMARY OF THE INVENTION In accordance with the present invention, the above objects are obtained by a unit having a hollow elongated housing having an upper outlet and a lower inlet.

First axially extending wall means, consisting mainly of a ring of parallel pipes welded together in gastight relationship generally cylindrical defines with the interior of the housing a closed axial compartment which acts as an insulating zone for the boiler.

Second axially extending annular wall means within the first, and similarly formed, define an annular axially elongated chamber open at its upper end toward the outlet and at its lower end toward the inlet, This second wall further defines an axial bypass passage through the center of the housing, with a valve in the passage serving to regulate air flow therethrough and thereby force air at a measured rate through the chamber. Each wall is formed by a respective member of a pair of coaxial, separable, but nested members. Means for passing liquid through both walls is provided in the form of the customary pumps and loads.

The boiler, according to the present invention, solves several problems in a surprisingly effective manner. It permits the adjustment of the heat-exchange rate by means of a valve which determines the proportion of the hot air which passes straight through the central bypass passage and the proportion diverted through the exterior heat-exchange chamber which is, according to another feature, provided with its own heat exchanger means in the form of axially extending pipes. Cleaning is easy since the housing, first wall, and second wall can be easily separated from each other by axially displacing them relative to each other. The outer insulating chamber formed between the first wall and the: housing insulates well while adding no additional weight to the device.

DESCRIPTION OF THE DRAWING The above and other objects, features, and advantages will become more fully apparent in the following description, reference being made to the drawing, in which:

FIG. 1 is an axial section through a boiler according to the present invention;

FIG. 2 is a similar section showing the boiler partially pulled apart for cleaning; and

FIGS. 3-5 are transverse sections taken along lines III-III, IV-IV and V-V respectively.

SPECIFIC DESCRIPTION The boiler comprises basically an elongated, cylindrical housing 1 consisting of a base 17 formed with an inlet 16 and lined with refractory brick 19, a central wall section 6, and an upper endpiece 14 mounting a conduit 37 serving as outlet 15.

Within this housing 1 are a plurality of generally axially extending pipes 3 through which water is circulated via pumps as will be described below. Between the pipes 3 are spaces 2, and an empty central axial bypass passage 4 completely free of heat-exchanger pipes 3 extends up through the boiler. The outer row of pipes 3, those most remote: from the housing axis A, are all longitudinally joined by welding so that they form a gastight wall 7. This wall 7, along with a steel bellows 20 abutting a flange portion 28 of a central housing ring member 18 by means of a ring 27, and a steel bellows 21 welded to the top 14 and to a manifold 13 for the pipes 3, form a substantially closed compartment 38. Since feeder pipes 8 and 9 for the pipes 3 and the circular manifolds 13 for these pipes are in this closed annular compartment 38, the gas therein is cooled, thereby obviating any necessity oflining the housing 1 with insulation, the relatively cool gas in the compartment 38 serving very well as insulation.

The inner row of pipes 3 is similarly welded together to form a wall 33. Here, however, every other pipe is bent out at both the upper and lower ends of this wall 33 to form openings 12 through which gas can pass.

The conduit 37 is formed with two axially spaced sets of apertures 25 and 26 either of which can be blocked by a valve body in the form of a slider 5. A control rod 24 mounts this slider 5 which is in the form ofa hollow cylindrical shell and is axially displaceable in the conduit 37.

The top 14 of the housing 1 is provided with a large hole through which pass feeder pipes 39 for the wall 33 and the conduit 37, its flange 40 defining an annular gap therewith. A circular ring 22 of insulating material seals this gap. The outwardly flared lower ends of the pipe array forming the wall 33 lead out through a potted seal 34 and through the ring 18 to join one of the manifolds 13. A pump 29 and a load 30 are connected in series with the pipes of the wall 33 to pump water up through them, while a similar pump 31 in series with load 32 pumps water up through the wall 7 and the heatexchanger pipes 3 between walls 33 and 7.

The pipes 3 forming the wall 7 and in the space 10 between the wall 7 and the wall 33 are rigidly connected to the top 14 of the housing 1. Bolts 35 hold the top 14 and the middle section 6 together while bolts 36 clamp the ring 18 and the base 17 of the housing together.

In normal Operating conditions, hot compressed gas enters the boiler at 16. If the slider 5 is in its lowered position, it blocks the apertures 26 and the gas will flow mainly up through the spaces 2 between the pipes 3 in the chamber between the walls 7 and 33. The water in these pipes is heated and transformed into steam which is used to do work in the loads 30 and 32 which are, for example, steam turbines. Should there be no need for such steam, or only a minor need, the member 5 is lifted to block the apertures 25 so that the gas flows straight up the pipe-free bypass passage 4, into the openings 26 and out through the outlet 15. During this type of operation only a slight amount of water is pumped by the pumps 29 and 31 to prevent damage to the boiler.

In order to clean, repair or inspect the boiler, the bolts 35 and 36 are removed. The sections 14, 6, the ring 18 and the base 17 are then all pulled axially apart, as shown in FIG. 2. It can be seen that the wall 33 and the insulation ring 22 pull away from the upper section, while the conduit 37 can even be pulled up out of the housing 1. The section 6 can be dropped so that the pipes 3 are all completely exposed. Pipes 41 connected to the manifold 13 of the pipes forming the wall are rigidly fixed in the top section 14.

In practice, a boiler as described above can be used in either the upright or horizontal position, the former being generally preferred. Furthermore, the waste-heat boiler herein described is advantageously used in series with a boiler having no valve and no bypass passage, such as that described in German Pat. No. 1,027,685.

As is readily apparent from FIG. 2, the apparatus may be assembled by permanently mounting the outlet duct so that it remains axially fixed or setting this outlet duct in place so that its annular transverse flange 40 is as the location desired for the upper hood or dome 14 of the housing. This dome or hood, which carries the header 13a for the water tubes 3 of the outer chamber 2, is then urged axially upwardly (arrow B in FIG. 2), until its collar 60, having an inwardly turned edge 61, is in alignment with the flange 40, i.e., is coplanar therewith in a plane extending transversely to the axis of the device. At this point, the intermediate section 6 of the housing, which is cylindrical, may be urged axially upwardly (arrow C) to define with the wall 7 of welded pipe, the outermost compartment 38 in which the risers 8 and 9 are provided. It will be recalled that the bellows-type seals and 21, together with the gastight welding of the pipes 7 in contiguous relation (FIG. 3), ensure that compartment 38 will remain substantially free of the hot gases and is heated only by conduction.

At this point the bypass member of the assembly of coaxially nested bodies may be inserted axially upwardly with the space enclosed by the nest of spaced-apart tubes 3 to establish wall 33 of interconnected and gastight pipes forming the bypass channel. The lower portion 23 of the outlet duct 15 extends axially into this bypass channel which is formed with a pair of ring-shaped discs 62, 63 which are welded to the inner wall 33 of the bypass passage and define a pair of axially aligned openings 64, 65 closely receiving the tube 15. Thus, when the valve 5 is closed, the bypass passage cannot be traversed by the hot gases. The bypass member of the assembly is axially advanced upwardly (arrow D) until the upper surface 66 of the heat-resistant potting compound 22, in which the header 13b is anchored, engages the underside 61 of the collar 60 and the underside 67 of the flange 40 to provide a seal between the bypass passage and the outlet tube 15 on the one hand and between the outer chamber 2 and the housing portion 14 on the other hand. This operation, moreover, brings the upper surface 68 of the potting mass 34 and the ring 18, in which the outwardly turned ends of the tubes of wall 33 are imbedded into engagement with the underside 69 of the flange 70 of intermediate housing portion 6 to form a gastight seal here as well. An upwardly turned cylindrical tubular boss 71 along the inner boundary of the mass 34 cooperates with the ring 27 and the bellows 28, previously mentioned, to seal the compartment in which the tube bundle 3 is provided. It will be recalled that the bypass channel is free from tube bun dles.

Thereafter, the inlet tube or member 16, 17, 19 may be applied so that its flange 72 sealingly engages the underside 73 of the ring 18. Of course, disassembly is in the opposite direction and the parts may be assembled and disassembled in the reverse manner. In this case, the inlet member 16, 17, 19 will first be fixed and the bypass member seated thereon to be followed by intermediate housing portion 6, dome 14 and the associated pipes, and the outlet duct 15.

When the valve 5 is closed, i.e., passages 26 are blocked, the gas entering through the inlet 16 flows in the direction of arrow E into the surrounding chamber and thence through the 1 latter (arrow F), in heat exchange with the tubes 3, finally emerging (arrow G) beyond the barriers 62 and 63 to flow into the outlet 15 through the windows 25. When, however, the valve 5 is opened, the principal flow is via openings 26 (arrows H) into the outlet 15.

I claim:

1. A gas-liquid heat-exchange unit comprising:

a hollow elongated housing having an inlet at one end and an outlet at the other end;

first axially extending annular wall means defining with the interior of said housing a closed axially extending annular compartment;

second axially extending annular wall means within said first wall means and forming therewith an annular axially elongated chamber open at one end toward said inlet and at the other end toward said outlet, said second wall means forming an axially extending substantially central bypass passage having one end open toward said inlet and another end open toward said outlet, said wall means each being formed by a respective member of a pair of substantially coaxial axially relatively displaceable separable nested members; and

means for passing liquid through both said wall means and valve means in said passage between the ends thereof for selectively blocking gas flow through said passage and thereby forcing gas to flow through said chamber.

2. The unit defined in claim 1 wherein said housing constitutes a third member substantially coaxially nested with said two first-mentioned members.

3. The unit defined in claim 1 wherein said housing is arranged upright and said input is below and substantially axially in line with said output.

4. The unit defined in claim 1 wherein said valve means includes an axially displaceable slider displaceable into and out of a position blocking said gas flow.

5. A gas-liquid heat-exchange'unit comprising:

a hollow elongated housing having an inlet at one end and an outlet at the other end;

first axially extending annular wall means defining with the interior of said housing a closed axially extending annular compartment; second axially extending annular wall means within said first wall means and forming therewith an annular axially elongated chamber open at one end toward said inlet and at the other end toward said outlet, said second wall means forming an axially extending substantially central bypass passage having one end open toward said inlet and another end open toward said outlet, said wall means each being formed by a respective member of a pair of substantially coaxial separable nested members; means for passing liquid through both said wall means and valve means in said passage between the ends thereof for selectively blocking gas flow through said passage and thereby forcing gas to flow through said chamber; and

heat exchanger means in said chamber between said wall means.

6. A gas-liquid heat-exchange unit comprising:

a hollow elongated housing having an inlet at one end and an outlet at the other end;

first axially extending annular wall means defining with the interior of said housing a closed axially extending annular compartment;

second axially extending annular wall means within said first wall means and forming therewith an annular axially elongated chamber open at one end toward said inlet and at the other end toward said outlet, said second wall means forming an axially extending substantially central bypass passage having one end open toward said inlet and another end open toward said outlet, said wall means each being formed by a respective member of a pair of substantially coaxial separable nested members; and

means for passing liquid through both said wall means and valve means in said passage between the ends thereof for selectively blocking gas flow through said passage and thereby forcing gas to flow through said chamber, said wall means each consisting ofa plurality of axially extending conduits joined longitudinally.

7. The unit defined in claim 6 wherein said members are axially displaceable relative to each other.

8. A gas-liquid heat-exchange unit comprising:

a hollow elongated housing having an inlet at one end and an outlet at the other end;

first axially extending annular wall means defining with the interior of said housing a closed axially extending annular compartment;

second axially extending annular wall means within said first wall means and forming therewith an annular axially elongated chamber open at one end toward said inlet and at the other end toward said outlet, said second wall means forming an axially extending substantially central bypass passage having one end open toward said inlet and another end open toward said outlet, said wall means each being formed by a respective member of a pair of substantially coaxial separable nested members; and

means for passing liquid through both said wall means and valve means in said passage between the ends thereof for selectively blocking gas flow through said passage and thereby forcing gas to flow through said chamber, said housing comprising a top section, a middle section, and a base section, all three said sections being axially displaceable relative to one another.

9. The unit defined in claim 8 wherein said second wall means is displaceable relative to said sections.

10. The unit defined in claim 9, further comprising heat exchanger means including a plurality of axially extending pipes in said chamber between said walls, said outlet being a conduit extending axially into said passage, said valve means being in said conduit, said housing further comprising a ring between said middle section and said base section, said wall means each being a plurality of longitudinally joined pipes, the pipes of said second wall means extending out of said housing through said ring, said first wall means including a first substantially circular manifold received in said top section and a plurality of feeder pipes passing through said top section and extending substantially axially, said first wall means further including a substantially circular second manifold received in said top section surrounding said conduit and a substantially circular ring of insulating material, said second manifold being at least partially embedded in said ring block and said block tightly abutting said top section. 

1. A gas-liquid heat-exchange unit comprising: a hollow elongated housing having an inlet at one end and an outlet at the other end; first axially extending annular wall means defining with the interior of said housing a closed axially extending annular compartment; second axially extending annular wall means within said first wall means and forming therewith an annular axially elongated chamber open at one end toward said inlet and at the other end toward said outlet, said second wall means forming an axially extending substantially central bypass passage having one end open toward said inlet and another end open toward said outlet, said wall means each being formed by a respective member of a pair of substantially coaxial axially relatively displaceable separable nested members; and means for passing liquid through both said wall means and valve means in said passage between the ends thereof for selectively blocking gas flow through said passage and thereby forcing gas to flow through said chamber.
 2. The unit defined in claim 1 wherein said housing constitutes a third member substantially coaxially nested with said two first-mentioned members.
 3. The unit defined in claim 1 wherein said housing is arranged upright and said input is below and substantially axially in line with said output.
 4. The unit defined in claim 1 wherein said valve means includes an axially displaceable slider displaceable into and out of a position blockIng said gas flow.
 5. A gas-liquid heat-exchange unit comprising: a hollow elongated housing having an inlet at one end and an outlet at the other end; first axially extending annular wall means defining with the interior of said housing a closed axially extending annular compartment; second axially extending annular wall means within said first wall means and forming therewith an annular axially elongated chamber open at one end toward said inlet and at the other end toward said outlet, said second wall means forming an axially extending substantially central bypass passage having one end open toward said inlet and another end open toward said outlet, said wall means each being formed by a respective member of a pair of substantially coaxial separable nested members; means for passing liquid through both said wall means and valve means in said passage between the ends thereof for selectively blocking gas flow through said passage and thereby forcing gas to flow through said chamber; and heat exchanger means in said chamber between said wall means.
 6. A gas-liquid heat-exchange unit comprising: a hollow elongated housing having an inlet at one end and an outlet at the other end; first axially extending annular wall means defining with the interior of said housing a closed axially extending annular compartment; second axially extending annular wall means within said first wall means and forming therewith an annular axially elongated chamber open at one end toward said inlet and at the other end toward said outlet, said second wall means forming an axially extending substantially central bypass passage having one end open toward said inlet and another end open toward said outlet, said wall means each being formed by a respective member of a pair of substantially coaxial separable nested members; and means for passing liquid through both said wall means and valve means in said passage between the ends thereof for selectively blocking gas flow through said passage and thereby forcing gas to flow through said chamber, said wall means each consisting of a plurality of axially extending conduits joined longitudinally.
 7. The unit defined in claim 6 wherein said members are axially displaceable relative to each other.
 8. A gas-liquid heat-exchange unit comprising: a hollow elongated housing having an inlet at one end and an outlet at the other end; first axially extending annular wall means defining with the interior of said housing a closed axially extending annular compartment; second axially extending annular wall means within said first wall means and forming therewith an annular axially elongated chamber open at one end toward said inlet and at the other end toward said outlet, said second wall means forming an axially extending substantially central bypass passage having one end open toward said inlet and another end open toward said outlet, said wall means each being formed by a respective member of a pair of substantially coaxial separable nested members; and means for passing liquid through both said wall means and valve means in said passage between the ends thereof for selectively blocking gas flow through said passage and thereby forcing gas to flow through said chamber, said housing comprising a top section, a middle section, and a base section, all three said sections being axially displaceable relative to one another.
 9. The unit defined in claim 8 wherein said second wall means is displaceable relative to said sections.
 10. The unit defined in claim 9, further comprising heat exchanger means including a plurality of axially extending pipes in said chamber between said walls, said outlet being a conduit extending axially into said passage, said valve means being in said conduit, said housing further comprising a ring between said middle section and said base section, said wall means each being a plurality of longitudinally joined pipes, the pipes of said second wall means extending out Of said housing through said ring, said first wall means including a first substantially circular manifold received in said top section and a plurality of feeder pipes passing through said top section and extending substantially axially, said first wall means further including a substantially circular second manifold received in said top section surrounding said conduit and a substantially circular ring of insulating material, said second manifold being at least partially embedded in said ring block and said block tightly abutting said top section. 